StringConverter generates unknown C++ exception

Hi everybody!

I'm here again with Converter plugin.

Working with ruby on Windows. Ice version — 3.4.1.

config.client:

# Warn about connection exceptions
Ice.Warn.Connections=1

# We want a faster ACM for this demo.
Ice.ACM.Client=10

# Network Tracing
# 0 = no network tracing
# 1 = trace connection establishment and closure
# 2 = like 1, but more detailed
# 3 = like 2, but also trace data transfer
Ice.Trace.Network=2

# Protocol Tracing
# 0 = no protocol tracing
# 1 = trace protocol messages
Ice.Trace.Protocol=1

#Ice.Plugin.Converter=Ice:createIceStringConverter windows=1251
Ice.Plugin.Converter=Ice:createStringConverter iconv=UTF-8 windows=1251

Ruby code:

initialization_data = Ice::InitializationData.new
initialization_data.properties = Ice::createProperties
initialization_data.properties.load(File.dirname(__FILE__)+'/config.client')
@communicator = Ice::initialize([], initialization_data)

the last line dies with:

RuntimeError: caught unknown C++ exception

Any ideas? How do I understand where to dig further?

PS. If I comment last line in config.client everything works ok.